A filesystem in a source storage server can be replicated in a destination storage server. One example for replicating the file system is the SnapMirror® technology which is commercially available from Network Appliance, Incorporated. The SnapMirror technology will transfer all or some of the blocks of the container volume image of the source storage server to the destination storage server. An example of the SnapMirror technology is disclosed in, for example, commonly-assigned U.S. Pat. No. 7,143,307.
A related technology, “snapmirror to tape” (SM2T), allows users to capture the image of the filesystem to a locally attached tape instead of replicating the filesystem to a remote storage server. Optionally, users may store the filesystem image in the form of a file on the local filesystem (in the source storage server) Instead of using a tape. The SM2T image, whether stored on tape or in the form of a file, may be restored on the destination storage server to reconstruct the entire filesystem in its particular state when the SM2T backup was taken. An SM2T image is one example of an image that can be stored in the form of one or more files on a disk. Currently, this is the only way a SM2T backup file can be used. As an example, in order to restore a small 10 KB file, the user may have to restore (on a destination storage server) the entire SM2T backup image which may be multiples of terabytes in size. Not only must the destination storage server have enough storage space to restore the entire filesystem, it must also meet certain configuration requirements, failing which, the restore may not succeed or may proceed extremely slowly. Customers have used Snapmirror-to-tape technology to back up filesystems which contain very large number of files, because a regular filer dump application is typically too slow. However, to restore, e.g., only one file or only a few files, users must restore the entire volume to a destination storage server, and this requirement will require sufficient free disk space in the destination storage server or disadvantageously require current data to be overwritten on the destination storage server. As a result, current approaches are burdensome to users because these approaches require the restoration of the entire filesystem image from a disk to the destination storage server even if a user will only intend to back up, e.g., one or only a few files of the filesystem image, to the destination storage server. Users are currently unable to selectively extract the one or few files of the filesystem image from the disk and copy these one or few files to the destination storage server for purposes of backup. Therefore, the current technology is limited in its capabilities and suffers from at least the above constraints and deficiencies.